For applications that require quality of service (QoS) assurances, the best effort service model commonly used to transmit information over the Internet is proving inadequate. In general, assuring QoS entails providing differentiated services for certain packet-level or session-level treatment; that is, some users receive higher priority treatment or have a greater bandwidth allocation than other users.
Approaches to managing data traffic for providing differential services fall into two categories, those with network-wide reservations that include explicit signaling and those without such network-wide reservations. Reservation-based traffic management explicitly identifies and reserves network resources. Network nodes categorize data traffic into classes and provide QoS using the network resources reserved for the particular class associated with incoming data traffic. One example of network-wide reservation-based traffic management is the Integrated Services (IntServ) model, which uses the per-flow approach to provide guarantees to individual data streams and makes reservations of resources at intermediate routers.
In traffic management that does not use network-wide reservations, but can use local reservations at a router, the network nodes classify data traffic into a set of classes and use the classes to grant priority-based treatment to the traffic. An example of such traffic management is the Differentiated Services (DiffServ) model. DiffServ provides aggregate assurances for a group of applications.
Today, many of the communication links between the various communications entities in networks are wire-line; that is, client and server systems are typically connected to other server and client systems by wires, such as twisted-pair wires, coaxial cables, fiber optic cables, and the like. Notwithstanding this wired infrastructure, wireless networks such as cellular and Personal Communication Systems (PCS) and wireless local area networks, microwave links, infrared (IR) links, and satellite links are becoming more prevalent. Wireless devices connected to such networks are typically mobile. Such mobility creates frequent, dynamic changes to the network topology. Moreover, the peculiarities of signal propagation over wireless links cause frequent changes to the state of such communication links between the devices on the network. Consequently, nodes in wireless networks need to deal with higher data losses and frequent bandwidth reallocations.
The initial designs of the IntServ and DiffServ models, however, contemplated wired networks only and are not suited for the various characteristics of wireless networks. Thus, there remains a need for a system and a method that can manage traffic in a wireless network to provide QoS assurances despite the aforementioned difficulties associated with the mobility of the communication devices and propagation conditions encountered in the wireless networks.